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6 GUMVINES The latex-filled stems of the genus Landolphia1 once produced all the rubber for Senegal and Sudan and some of the rubber for other African nations. Part of the harvest was even exported to Europe, where it was esteemed. Commercial interest in these plants collapsed only when, in the early 1900s, Brazil’s rubber tree (Hevea brasiliensis) began dominating world production. The problem was not the quality of the rubber. The African plants were superseded because, being vines or climbing shrubs, they are hard to handle in horticulture. Further, they had never been brought into organized cultivation, and harvesting latex from scattered wild plants cannot compete with organized plantation production, even in the rubber tree itself. During World War II, when the Allied Powers were cut off from Southeast Asia’s huge rubber production, interest in Africa’s so-called gumvines picked up once more. However, the wartime crisis passed before much product could be supplied. The subsequent perfection of synthetic elastomers then seemed to forever seal the fate of Africa’s own native rubber supply. People gave up on these crops, which have since remained mere curiosities of minor local historical interest. Now, however, international interest should pick up once more. Some Landolphia species bear masses of fruits that are very pleasant to the taste buds. A few of these “gumvine fruits” or “rubber fruits” are yellow and furry and look somewhat like apricots; most, however, are more like an orange with smooth tough skins that are reddish, yellow, or orange in color. These fruits are frequently seen for sale in markets across West Africa. In Mali, Burkina Faso, and neighboring nations it is also common to see young boys selling clusters of them along the roadways. The juice from these fruits is regarded as extremely healthful, probably with good reason. In addition to a normal nutritional content for fruits, some have vitamin C levels approaching oranges. At least one species, Landolphia hirsuta, provides 1 Landolphia taxonomy is tangled, with much overlap among scientific and common names. Further, some botanists transfer all Landolphia species to the genus Saba, some refer a number of them, including L. capensis and L. kirkii, to Acylobothrys. However, most of the literature is still to be found under Landolphia. 271

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LOST CROPS OF AFRICA 272 Landolphia lanceolata photographed beside a highway in western Congo (D.R. Congo). Boys peddling clusters of gumvine fruits are a common sight across West and Central Africa. The fruits are sweet, juicy, and can provide good provitamin A. Of all Central Africa’s fruits these are the ones most commonly offered in markets and along the roadsides. This popular food remains a wild resource, but it holds much promise to help rural peoples produce highly salable products in some of the world’s most horticulturally challenged regions. (Paul Latham) good levels of provitamin A, and all gumvines share the same tell-tale yellowish carotenoid color. People often use them to season rice, maize, and other cereals; to prepare refreshing, lemonade-like drinks; to make a type of beer; and to flavor foods such as fish. In The Gambia, and perhaps elsewhere, gumvine is used this way as a condiment in place of limejuice. At least 17 Landolphia species—perhaps a hundred or more—occur in tropical savannas and forests, notably in West and Central Africa. They are common forest lianas and sprawly shrubs noted for their jasmine-scented flowers as much as for their plentiful fruits or latex-filled stems. Currently, little importance is attached to the plants as potential income sources. But if they can be tamed and turned to use, tropical Africa will have a collection of new, interesting, and appealing crops that could contribute much to nutrition and perhaps much to economic well-being as well. If particularly good specimens can be located and produced in quantity, there is even the possibility of exports, because these fruits tend to have shelf lives long enough for ocean travel. All in all, rubber fruits offer good projects for plant lovers and progressive farmers throughout the African tropics. In addition, scholars in France, Belgium, Germany, and Britain could help the cause by scouring the

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GUMVINES 273 colonial archives and botanical records for horticultural information recorded during both World War II and the earlier rubber-producing era. This could be most useful because the musty old documents are difficult for outsiders to access today, and the results of all the earlier work are essentially lost to worldview. Even armed with such information, organizing rubber-fruit production will not be easy. Viney plants are horticultural horrors. They require supports, and their climbing or spreading growth habit makes them hard to manage. Nonetheless, the world’s biggest fruit crop (grapes) comes from a vine, as do some fast-developing newcomers (kiwifruit and passionfruit, for example). Adapting management techniques from those (or from vanilla, for that matter) may provide the keys for domesticating rubber fruits. In this regard, then, pruning, training, and general horticultural improvement should be explored. In addition to using trellises and pergolas, the concept of training these vines on trees should be evaluated. If successful, rubber fruits could raise the economic value of standing forests— thereby dampening the ardor to burn those forests down for land or cut them up for lumber. Perhaps rubber fruits could also help shifting-cultivators by providing food and income while they wait out the weary years for the land to restore itself. In fact, fruits in many other parts of this report might be used for such “fallow enhancement”—both protecting the soil and producing at least a small something to eat or sell on the side. Other agroforestry interventions should be tested as well. Incorporating gumvines into boundary tree rows, windbreaks, shelterbelts, and ex-situ conservation forests are possibilities.2 Plants such as these that cling onto something could be a way to increase the utility of many long-term environmental tree-plantings. On the other hand, caution is needed because these vines are vigorous and get to be very heavy if left unmanaged. Indeed, these vines would seem to be ideal wherever dense, interwoven “nets of living vegetation” could prove useful. In village settings they might also be trained along fences, up walls, or perhaps over roofs. Paralleling such endeavors should also be farmer-participation programs. This is needed because at present farmers offer more insights than science. Their experience together with researchers’ training make a uniquely powerful intellectual cocktail for progress. Wild stands are especially appropriate places for local participation. And any efforts to advance gumvine fruits should include in-situ conservation to preserve those stands. Despite all the promise and possibilities, organizing commercial production presents grave horticultural challenges. In the wild, gumvines do not fruit every year, nor do the plants form their fruits all at the same time. 2 The process of weaving vines among the trees is already practiced in Africa. An orchardist in Djenné, Mali, for example, plants a thorny climber (Acacia pennata) among neem trees to create a barrier to both wind and animals. Malians also plant thorny Capparis vines among their trees to equally good effect. Information from D. Osborn.

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LOST CROPS OF AFRICA 274 Also, it is reported that some species take as long as 12 months to mature each crop of fruits. However, such difficulties probably reflect merely our primitive state of knowledge. Although little effort has been made to propagate the vines, this seems not to be problematic. Freshly collected seed normally germinates well.3 Selected plants can also be propagated via cuttings. Production can be exceptional: Vines yielding 200 fruits have been recorded, and even better specimens undoubtedly await discovery. Indeed, throughout Africa gumvines are renowned for the often-enormous burden of fruits hanging around them on all sides. Genetic selection and domestication are important for turning gumvines into fruit crops. Finding quality types and developing horticultural methods that speed up production are two keys to success. Following are gumvines possessing potential as future fruit crops. RUBBER VINE The so-called rubber vine (Landolphia florida Benth.)4 is perhaps the most common gumvine. Its fruits are eaten in many parts of Africa. They are round or slightly pear-shaped and are about the size of grapefruits. Their thick and leathery rind is yellow to orange in color, dusted with a whitish “bloom” at maturity. The inside is full of soft, reddish pulp within which are embedded a few seeds. The succulent, smooth, and either sour or agreeably subacid pulp pulls away easily from the rind. Normally, the seeds are picked out and the remainder blended with water and sugar. The resulting beverage is consumed either fresh or fermented, and is said to be most pleasant. The species occurs in lowland rainforests and flourishes on a variety of sites and soils. It is a liana, climbing up the sides of trees as high as 20 m. Its stems are stiff enough to make useful walking sticks, and sometimes they are intertwined between fenceposts to construct corrals capable of holding cattle overnight. Fruits remain on the tree when ripe and can be “stored” there on the vine till needed. SABA The saba (Landolphia senegalensis (A. DC.) Kotschy & Peyr.)5 is an “upwardly mobile” plant of tropical West Africa and the western Sudan. 3 A success rate of over 90 percent has been reported, but apparently the seeds must be clean and fresh; dirty seeds lose viability in just weeks. 4 Synonyms are Landolphia comorensis, Landolphia comorensis variety florida, Saba florida, Saba comorensis, and Vahea senegalensis. Common names include rubber vine, aboli, saba du Sénégal (French), and anoma (Ghana). 5 A synonym is Saba senegalensis (A. DC.) Pichon.

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GUMVINES 275 Typically, this woody vine clambers up the fringes of the forest. It is a high climber when trees are available to support its ambition to get to the top, but in more open and dry lands it remains a lowly shrub. Saba fruits are orange on the outside and pale yellow inside. They have a thick, rough rind. Most are about the size of a medium to small orange. In taste, they are acidic, almost like a strange form of citrus, which they nearly match in vitamin C content. In parts of Africa, they are important to the rural economy, and many are trucked or carried in baskets to sell in the cities. These colorful treats are, for example, widely consumed in Senegal and the Gambia. They are full of big seeds that are coated with an aromatic sweet and sour flesh. Most are eaten as casual snacks, but some are employed even as a staple—especially during the rainy season. They are also blended with water and sugar and made into fruity beverages. One of our contributors calls them, “fantastic for exotic juice.” The vines themselves have uses too. They make beautiful ornamentals. And they do more: homeowners even use the almost unbreakable vines to tie down their roofs. In addition, the latex-filled sap is used to mend bicycle tires, football bladders, and so forth. And the long lianas are made into “ropes,” with which to scale trees (for tapping palm-wine, for instance, or collecting nuts). WILD APRICOT One of the plants English speakers in tropical and southern Africa refer to as “wild apricot” is actually a native rubber fruit (Landolphia capensis Oliver). This sprawling shrub, for example, rambles over rocky ground in South Africa (notably Gauteng). In season, groups are commonly organized to go out and gather the large, yellowish-red fruits on the hillsides and plains. Their tasty flesh can be sucked directly, but the parts immediately around the seeds are very sour. The fruits are also fried or made into preserves, jellies, vinegar, or “brandy.” Like its relatives, this plant’s stems ooze latex when cut. WILD PEACH This strong climber (Landolphia kirkii) abounds on rocky, wooded hillsides in eastern and southern Africa (Somalia to South Africa), especially in the high-rainfall parts. In the past it was East Africa’s most important rubber plant. The extracted latex is of good quality: high in rubber, low in resin. It was once known worldwide under the name “Zanzibar rubber” and was a major export of German East Africa (today’s Tanzania). As a result of past commercial significance, the species was sometimes cultivated. Colonial records contain information on planting, managing, and tapping for latex. Today, the plant is rarely if ever cultivated—and perhaps there is no need as it is plentiful in the forests, where it readily reseeds itself.

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LOST CROPS OF AFRICA 276 EATING ETA After cracking open an eta fruit one sees the seeds and pulp clinging together in a tight ball, quite loose from the outer shell. People eat this in different ways. Some use a finger, knife, or other utensil to separate the seeds so they can be eaten individually. Others tip back their heads and shake the whole mass into their mouths. Most of us do it that way, swallowing the seeds after swishing the fruit around for just a couple of seconds. Speed is needed because the aromatic sweetness soon turns sour and intensifies until almost unbearable. We found one eta fruit, however, that never turned sour. Eating it was a whole new experience. Also, the flesh was separated from the seeds, an exceptionally desirable trait. Seeds from this particular fruit were planted at our experimental fruit farm in Congo, but we don’t yet know if they too will bear sweet and cling-free fruits. The point is, a lot of variation is to be found and it might provide many unexpected ways for advancing this crop. (Roy Danforth and Paul Noren) Fruits of this gumvine are round, speckled, and sized like mandarin oranges. They are popular with those in the know, but their tartness can put off the uninitiated. GUINEA GUMVINE Despite its common name, guinea gumvine (Landolphia heudelotii A. DC.) occurs throughout most of tropical Africa from Senegal to Tanzania

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GUMVINES 277 and as far south as the Congo area or even Angola. It is a characteristic feature of the vegetation on the interior plateaus throughout this vast area. Mainly a savanna and understory shrub, it is often found in open forests and on laterite and sandy soils near rivers. This climbing vine or spreading shrub once was the main rubber supplier to Senegal, Guinea, and the French Sudan (modern Mali). Some of its rubber reached Europe. A century ago, farmers were encouraged to cultivate the plant in gardens and farms, particularly after the wild vines were so decimated that the rubber supply began dropping. Propagation was both by seeds and cuttings. The sap is even today used locally to fix bicycle tubes. However, the fruits are now much more important than the rubber. Small (3 cm in diameter), round, and yellow to orange in color, they sell well in markets. The pulp surrounding the seeds is filled with a juice that is regarded as very healthful and is sometimes prescribed as an aid to digestion. Rich in organic acids, this pulp is used as a snack, as a breakfast food, and as a source of refreshing drinks. Beer is also made, and the juice is commonly used to season rice with its sprightly sourness. In some countries—The Gambia, for instance—it is especially important during the “hungry time” each year. The plant grows under trees and is promising for agroforestry. Farmers are likely to grow it eagerly, whether they really want fruits or not. To them, it is a self-replenishing annual fodder reserve. Goats like the desiccated leaves, and the plants thereby help a farmer’s “cash on the hoof” survive the dry season. ETA The eta (Landolphia owariensis Beauv.) is found in tropical Central and West Africa.6 It grows as a vine in forest; as a shrub in savanna. At the turn of last century it was a major source of rubber produced in Sierra Leone, Ghana, Nigeria, and perhaps other nations as well. Today people make rubber bands out of the cured latex, but this is increasingly rare. The fruits, however, are widely eaten. They are the size of oranges and have a reddish-brown, woody shell and an agreeable pulp. This pulp is eaten directly. It is also used to season foods and to make tangy fruit drinks and even wine. Typically, the flavor is both sweet and sour at the same time. Eta is an unusual fruit, but people really like it. Normally, the pulp is merely dumped in water and left to soak a few minutes. Being highly acidic, it makes a lot of beverage. Sugar is added to taste, and the final product conveys a delightful aroma. The tough and leathery skin is usually opened with a whack of the fist or heel of the hand. (It can be cut open, but latex in the thick outer shell soon gums up the knife.) 6 It is also known as abo and Congo rubber.

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LOST CROPS OF AFRICA 278 Seeds and cuttings are the usual means of propagation.7 For the first couple of years the plants are slow growing and remain short and stubby bushes, but they then begin elongating and take on the appearance of vines. At that time they are removed from the nursery and planted in the field. If given a chance, this gumvine grows straight up the trunks of trees, making its way to the top of the forest canopy. The twigs, like other gumvines, are also used as chewsticks. OTHER GUMVINES Below are mentioned several other species worthy of evaluation, which should be based on a fruits’ qualities rather than taxonomy. Landolphia petersiana Dyer This little-known eastern African gumvine bears apricot-colored, pear-shaped fruit that some experts consider to have more potential than wild peach (p. 275). It is sweeter, tastier, and more attractive than its better-known cousin, and therefore, they say, more saleable. Its flavor has been likened to guava, but so far no one has done much to explore the plant’s crop potential. The fruit is found in essentially the same range as wild peach—from Natal in South Africa through Mozambique and Tanzania, north as far as Somalia. It, too, is associated with tropical forest and bush. The plant is a sprawling shrub or woody liana, with tendrils. Its sweetly scented white flowers are cluster in panicles at the end of the branches. The fruit is more or less round, with numerous seeds embedded in the soft pulp. It is eaten when both ripe and nearly ripe. The ripe fruit is eaten skin and all, but the semi-ripe fruit must be first peeled. Landolphia ugandensis Stapf This large vine, the source of nandi rubber, is found at elevation (1,200-1,500 m) in Uganda. The rubber is obtained by shaving off slices of the bark and smearing salt water onto the cut surfaces, which then ooze latex. Landolphia buchananii Stapf Generally associated with forested environments in eastern Africa (Mozambique, Tanzania, and eastern Zimbabwe are reported), this vine bears yellow fruits as big as oranges. Landolphia parvifolia K.Schum. A plant found mainly on the shores of lakes in Malawi as well as in nearby Zambia, this gumvine bears edible greenish-purple fruits the size of plums or peaches. Landolphia calabarica (Stapf) E.A.Bruce This gumvine of Ghana has edible fruits up to 10 cm wide and 12.5 cm long. Rubber was once derived from the stems and roots. 7 Information from R. Danforth.

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GUMVINES 279 Landolphia dulcis var. barteri (Stapf) Pichon This pointy fruit, which looks not unlike a cocoa pod, is found in fallowed forest in West Africa.8 The roots are renowned for their supposed effectiveness as an aphrodisiac. Recorded in Senegal, common in ravine and gallery forests of moist climate ecozones. Also recorded as a sweetener in Sierra Leone. Landolphia hirsuta Beauvois is harvested from wild forests in Côte d’Ivoire. A rare nutritional analysis showed that merely three fruits (about 100 g edible portion) provide for almost 2/3 the daily vitamin A requirements of a 7-9 year old child.9 8 Information from S.C. Achinewhu. The plant is known in Nigeria as mbelekwulekwu. 9 Herzog F., Z. Farah and R. Amadò. 1994. Composition and consumption of gathered wild fruits in the V-Baoulé, Côte d’Ivoire. Ecology of Food and Nutrition 32:181-169.